taco test
A test one performs with one's contact lens (the soft kind only) after cleaning, to see whether it is inside out or not-- and whether it is ready to be inserted into one's eye. The taco test consists of the contact lens wearer placing the soft contact lens on a fingertip and attempting to bend the contact in half. If it closes on itself easily, it is right-side-out. If it springs back, it is inside out, and should be inverted before placed on the eyeball.
"My contact lens came out, I think it's inside out; should've done the Taco Test."